When a building, or part of one, is to be taken apart, if material is to be salvaged, nails must be extracted. Some parts of buildings, notably roofing materials, are intended to be replaced many times in the life of the building. Roofing materials, such as shingles, are nailed in place, so removing the shingles for replacement requires extracting the nails. For efficiency, it is normal to lift the roofing material and the nail together, until the nail is fully extracted and the roofing material is detached from the building. The roofing material and the nail can then be discarded, and the wooden roof that has been exposed will be retained, possibly with some repairs, and covered with new roofing material.
This description will mainly speak in terms of lifting shingles, for brevity. That is an important use of the tool, but it must be remembered that the tool is useful for removing many types of building materials held by nails.
Most nails have heads that provide a grip for a pulling tool. Most pulling tools have a slot to grip the nail below the head, and operate as a lever with the fulcrum on the surface in which the nail is embedded, such as the roof. The common claw hammer is an example. Many more elaborate tools have been developed, and patented, but there remains room for improvement in respect of the smoothness of operation in guiding the tool around the nail, and in levering the nail out of the material in which it is embedded.
U.S. Pat. No. 1,218,145 to Whittier discloses, way back in 1917, a shingle stripper that is a blade having V-shaped slots on the front and back edges, and the bottom surface (and top surface, but that is irrelevant) having two dihedral planes creating a single ridge fulcrum where the two planes meet. The present invention improves on the shape of the slots, and provides a continuous fulcrum as a curved rocker.
U.S. Pat. No. 4,203,210 to Hadlick discloses a shingle stripper that is essentially a shovel with V-shaped slots at the front edge, and a separate fulcrum affixed at the rear edge. Again, the present invention improves on the shape of the slots, and provides a continuous fulcrum like a curved rocker.
U.S. Pat. Des. 392,687 to Gracy et al. discloses a multi-purpose wrecking bar that has a flat bottom, so the only fulcrum is the rear edge. Gracy discloses slots with straight sides that taper either continuously, or in two different tapers, and some end the tapering straight side with a round hole.
U.S. Pat. No. 4,466,188 to Svendsgaard discloses a roofing remover that is wedge shaped and has slots that are straight parallel sides ending in a rounded end. The bottom surface is flat, but the tool as a whole is wedge shaped for forcing up the roofing material after the nail has been extracted. Extracting the nail involves lifting the nail by the slots, and the only fulcrum for lifting is the rear edge.
U.S. Pat. No. 5,280,676 to Fieni discloses an apparatus with slots having straight sides that taper in two different degrees, so the slot near the mouth of the slot converges rapidly and the remainder of the slot converges slowly or not at all. The bottom surface is almost all flat, but near the rear of the tool there is a bend that provides a ridge fulcrum before the rear edge comes into play as a fulcrum.
U.S. Pat. No. 6,125,720 to Gohman discloses a tool for removing roofing material that has slots much wider than a nail, and sub-slots within them that could seize a nail. All the slots have straight sides that taper narrower away from the leading edge. The blade is flat on the bottom (and top), but the manner of fastening it to the handle involves a curve that constitutes the rear edge for practical purposes. Most tools of this general type have the handle attached near the middle of the blade, but Gohman bends the blade and attaches the handle at the rear of the working surface of the blade. The bent rear edge of Gohman is not exactly a ridge fulcrum, but it is functionally different from the continuous curved rocker fulcrum of the present invention.
U.S. Design Pat. D439,126 to Gohman shows a thin blade with V-shaped teeth on the leading edge. The blade as a whole is partly flat and partly convex downward. It is quadrangular. The handle is attached at the rear of the blade, and the blade is not adaptable to have teeth on the rear edge. The prying force is delivered indirectly to the blade from the handle through an offset portion of the rear of the blade. As the blade has no reinforcing ribs or gussets, it is vulnerable to bending both along the main blade and in the offset joining the handle. This tool would require remarkably strong metal to operate with flexing.
U.S. Pat. No. 5,836,222 to Harpell discloses a shingle removing tool having slots with parallel sides, and an alternative with V-shaped slots. The bottom surface is flat, so the only fulcrum for lifting nails is the rear edge of the tool. The slots are simply parallel sides with rounded leading edges between them.
U.S. Pat. No. 6,029,545 to Harpell discloses a roofing tool having slots with parallel sides. The largest part of the bottom surface is flat, but blade is thinned near the leading edge so the bottom surface has a small portion near the leading edge that is a flat plane at a small angle to the rest of the bottom surface. Where the two planes meet, there is a ridge across the blade that serves as a fulcrum when the nail is first lifted. After a small advance of the nail, the fulcrum will shift to the rear edge of the blade, so this tool has two fulcrums, rather than the continuous rocker fulcrum of the present invention.
U.S. Pat. No. 6,098,292 to Harpell discloses a demolition tool having either no slots, or slots with parallel sides. The leading edge is designed for cutting, but cutting is often not desired, and rather grabbing and lifting is desired. It has a flat bottom, although with a groove, so its only fulcrum for leveraging nails upward is the rear edge. It has a quadrangular outline, which does not conform to a partially lifted shingle, and its sharp straight edges tend to cut the shingle, which is undesirable.
U.S. Pat. No. 6,339,975 to Harpell discloses long teeth on each side with straight sides, directing nails into slots that are rounded at the bottom and at the end of the finger between slots, but essentially have parallel sides. The bottom surface is flat, so the only fulcrum for lifting nails is the rear edge. The long fingers are very aggressive to the shingle, tending to cut, and pushing the long fingers much farther ahead than the slots where the nail will be lifted is inconvenient and hard work.
Published US application 20070051210 by Harpell discloses a tool blade with slots having two different degrees of taper near the mouth, and parallel sides to complete the slot. The bottom surface is two planes at a small dihedral angle, proving a fulcrum near the middle of the blade. There is also an alternative of a bottom surface that is flat through the middle majority of the surface, with a plane diverging at a small dihedral angle at each end. The present invention will improve on the design of the slots, and will provide a continuous fulcrum as a curved rocker. Harpell also provides an “impact receiving member” which is some distance up the handle above the blade. The present invention provides the equivalent hammer horns at a location that will better deliver the effect of impact to where it is helpful.